Problem: Which of these numbers is composite? ${61,\ 65,\ 71,\ 83,\ 97}$
Solution: A composite number is a number that has more than two factors (including 1 and itself). 61, 71, 83, and 97 each have only two factors. The factors of 65 are 1, 5, 13, and 65. Thus, 65 is the composite number.